All natural water supplies, regardless of source, are likely to contain some microbial organisms.
Luckily, only a very small percentage is known to cause disease, these are known as pathogenic organisms. Others, like algae, fungi and molds, contribute foul tastes, odors, or turbidity to the water.
The use of chlorination to disinfect water supplies has to a large extent eliminated the outburst of cholera and typhoid that were common before the turn of the century.
Chlorine-resistant pathogenic organisms can be very dangerous when they infect water supplies. They include a variety of viruses, bacteria, protozoans, amoebas, and parasitic worms.
Cryptosporidium is a protozoan which continues to show up in an increasing number of water supplies across the continent. This chlorine-resistant pest can overwhelm the body’s immune system.
Giardia lamblia is another cyst-forming protozoan responsible for the disease known as giardiasis, the number-one waterborne disease in North America. Giardiasis produces acute diarrhea, sometimes lasting for months, causing so much distress to the system that children, elderly people, and people in weakened conditions can die.
Cryptosporidium and Giardia has the ability to create a hard, protective coating. This coating protects the organism against normal chlorination procedures. Fortunately, Giardia as well as other forms of protozoan cysts are easily removed by reverse osmosis or fine filtration equipment (ceramic filters).
Bloodworms are a form of parasitic nematode or roundworms that are also chlorine resistant because of an ability to create cysts. They are appearing in municipal water supplies with increasing regularity.
Again, the infective forms of all parasitic worms are best removed by reverse osmosis or fine filtration at the point of use.
Viruses are the smallest of all pathogenic agents, some being as small as a single molecule. In general, viruses are both more dangerous and more resistant to disinfection than bacteria. With viruses, prevention is truly the best medicine. Some viruses can be removed by fine filtration, but ultraviolet light, distillation and ozonization are the systems of choice of combat these harmful agents.